Project Summary/Abstract Human cytomegalovirus (HCMV) causes debilitating and life-threatening disease due congenital and perinatal/postnatal transmission. There are no vaccines in clinical use to prevent HCMV disease. HCMV pneumonia occurs more frequently following perinatal/postnatal than congenital infection. Moreover, HCMV pneumonia continues as a significant cause of morbidity and mortality in HIV-exposed and infected infants. The route of transmission, developmental age, and underlying immune-deficiencies are all known contributors to the outcome of HCMV infection. Hypothesis driven research identifying viral determinants contributing to the initiation and progression of HCMV pneumonia are important to the overall goals of developing novel treatments and vaccines. From the pathology of HCMV pneumonia, it is suggested the virus causes alveolar damage and interstitial inflammation/fibrosis. Viral tropism within the tissue along with virus-induced cytokines are proposed to contribute to each outcome. Because HCMV does not infect small animals, the related murine virus, MCMV, has been used for studies of pneumonia in neonatal mice. These studies have identified infections in alveolar epithelial cells and macrophages as important to disease outcome. The overall goal of this project is to provide an in vitro cell model that effectively bridges observations made regarding the human disease and those made in animal model studies with state-of-the-art airway cell models. Currently available in vitro models of human tissue-derived 3D airway epithelium and myeloid cells will be evaluated in Aims 1 and 2. Aim 1 will address viral tropism in primary epithelial cell models in 3D cultures. Aim 2 will determine whether HCMV-induced cytokine expression in infected macrophages alters replication of HCMV in the epithelial cell model. Combined, the specific goals will systematically evaluate available airway models and address specific viral determinants that may promote alveolar damage. !